The present invention relates to apparatuses and methods for coffee-making machines and, more particularly to coffee-making machines that have semi-external heating elements.
Coffee-making machines, a term which is understood to include within it espresso-making machines, require heating water used for making the coffee or espresso, and also for making other hot beverages (e.g., tea) and steam (to foam milk). The water used in coffee-making machines is water in which there are a significant amount of dissolved minerals. This may be tap water or it may be bottled water containing minerals.
It is well known that heating water causes at least some of the minerals to precipitate out of solution either through evaporation of the water solvent due to the heat or through precipitation of the solute out of solution as fine particles. In either case, the particles that come out of solution gravitate to the bottom or side of the container or get accrued on devices dipped in the water, holding the solution as sediment. For example, calcium deposits are a common outcome of heating water.
When rain falls to the ground it dissolves limestone and chalk. Soluble bicarbonate of calcium and magnesium are dissolved in the water. When the water is heated, the soluble bicarbonates release insoluble calcium carbonate, which causes lime-scale.
It is well known that calcification and the deposit of lime scale are a continuing problem for coffee-making machines for several reasons. The calcium and lime sticks to everything that touches water. This includes the heating element, the water quantity measuring element and other sensors and other critical components. The build-up of scale reduces thermal efficiency by increasing the time it takes to reach the desired temperature. More importantly, the lime or calcium deposits interfere with proper functioning of the heating element. Heat transfer is impaired and energy efficiency is reduced. When the heating element malfunctions from the build-up of the scaly deposits, the heating element tends to overheat and be in a state of short circuit. As a result of the short circuit, the entire coffee-making or espresso-making apparatus may cease to function and even other systems connected to the same electricity line may be adversely affected by the short circuit.
As a result, machines that are supposed to last 10 to 20 years end up lasting 2 to 4 years. Accordingly, equipment replacement costs are astronomical. Labor costs for maintaining these coffee making machines are also high since a certified espresso machine technician is required in order to replace these heating elements. Their work takes several hours and the machine is down during that time, affecting business.
One thing that can be done to try to prevent build-up of lime and calcium on the heating element is to increase the frequency of maintenance checks. Chemicals for cleaning the lime and calcium also cost money. Consequently, increasing the frequency of maintenance checks increases labor costs and generates a significant increase in overall maintenance costs.
Prior attempts to solve this problem include the use of water softeners that are placed into the water. Water softeners exchange calcium and magnesium ions with twice as many sodium ions. This exchange is expensive to maintain, requires a lot of sale to operate and can require a lot of extra water. Environmentalists also maintain that water softeners pollute our environment by depositing chloride into our water supply. They may also harm people on salt restricted diets. The environmental objections has led to legislation—at the state or local level—by one count in approximately 34 states of the United States restricting the use of water softeners in sanitary sewage systems. In some countries, moreover, water softeners may be banned in the near future for environmental reasons. Water softeners allegedly also speed up pipe damage as more salty water flows through the piping.
An additional prior art attempt to solve the problem involves the use of filters in the coffee-making machines. Filters are expensive. In addition, the filters must be maintained properly, however, in order to be effective. In fact, the filters need to be replaced every couple of months. Applicant's experience in servicing coffee making machines over decades is that filters are simply not maintained properly. They are not replaced when they should be. A common reason, besides laziness, is that there is a frequent labor changeover in the retail outlets that use coffee-making machines and there is a constant shortage of trained personnel able to change the filters.
Another prior art solution is a dry external heating element installed around the water tank as an integral part of the water tank. This solves the problem of scaly deposits building up. However, it causes other problems. For example, in case of malfunction, the entire water tank utilizing the dry external heating element needs to be replaced. These heating elements are also expensive since they require very high power to compensate for the fact that the heat they emit is emitted away from the water tank. In addition, a certified espresso-machine technician is needed to service the heating element. Labor costs for servicing these dry external heating elements can take several days since these heating elements are extremely difficult to maintain. The heating element must also be fully in contact with the metal tank surface or a gap will be filled by air pockets that decreases the life of the heating element. However, to be fully in contact with the metal tank surface often results in the envelope that the heating element is encased in being expanded out of shape during use, which complicates replacement by the technician.
Applicant has also heard of a company on the Internet calling itself “Scalebusters” that offers a computerized system installed on the incoming water line of a facility. The computer system uses an oscillating electronic field that claims to change the physical size, shape and charge of calcium molecules. Although alleged to be less expensive than water softeners, this computer system is expensive to install and maintain.
There is a compelling need to have a method and apparatus for solving the build-up of lime and calcium deposits from water that adversely affects coffee-making machines.